Elastomer nanocomposites comprising isobutylene and multifunctional oligomers

ABSTRACT

The present invention provides a nanocomposite of an elastomer, a polymer or oligomer functionalized with a polar group, and a clay. The nanocomposite can be a mixture of a halogenated elastomer, an acid or acid anhydride modified polymer, and a clay, desirably an exfoliated clay, suitable for use as an air barrier. Also disclosed is a nanocomposite that can be a mixture of a halogenated elastomer, a polymer modified with a carboxylic acid, and an organoclay.

FIELD OF THE INVENTION

This invention relates to low-permeability nanocomposites useful for airbarriers, processes to produce the same, and their use in articles ofmanufacture.

BACKGROUND OF THE INVENTION

Nanocomposites are polymer systems containing inorganic particles withat least one dimension in the nanometer range. Some examples of theseare disclosed in U.S. Pat. Nos. 6,060,549, 6,103,817, 6,034,164,5,973,053, 5,936,023, 5,883,173, 5,807,629, 5,665,183, 5,576,373, and5,576,372. Common types of inorganic particles used in nanocompositesare phyllosilicates, an inorganic substance from the general class of socalled “nano-clays” or “clays.” Ideally, intercalation should take placein the nanocomposite, wherein the polymer inserts into the space orgallery between the clay surfaces. Ultimately, it is desirable to haveexfoliation, wherein the polymer is fully dispersed with the individualnanometer-size clay platelets. Due to the general enhancement in airbarrier qualities of various polymer blends when clays are present,there is a desire for a nanocomposite with low air permeability;especially a dynamically vulcanized elastomer nanocomposite such as usedin the manufacture of tires.

The preparation of nanocomposites uses a number of methods to generateexfoliated clays. One of the most common methods relies upon the use oforganically modified montmorillonite clays. Organoclays are typicallyproduced through solution based ion-exchange reactions that replacesodium ions that exist on the surface of sodium montmorillonite withorganic molecules such as alkyl or aryl ammonium compounds and typicallyknown in the industry as swelling or exfoliating agents. See, e.g., U.S.Pat. No. 5,807,629, WO 02/100935, and WO 02/100936. Other backgroundreferences include U.S. Pat. Nos. 5,576,373, 5,665,183, 5,807,629,5,936,023, 6,121,361, WO 94/22680, WO 01/85831, and WO 04/058874.

One method to improve the organoclay performance is to usefunctionalized polymers to treat the clay. This approach uses materialsthat are soluble in water or materials that can be incorporated into thepolymerization reaction. This approach has been used to prepare nylonnanocomposites, using for example, oligomeric and monomeric caprolactamas the modifier. Polyolefin nanocomposites, such as polypropylenenanocomposites, have utilized maleic anhydride grafted polypropylenes toachieve some success in the formation of nanocomposites.

For example, it is known to utilize exfoliated-clay filled nylon as ahigh impact plastic matrix, such as disclosed in U.S. Pat. No. 6,060,549to Li et al. In particular, Li et al. disclose a blend of athermoplastic resin such as nylon; a copolymer of a C₄ to C₇ isoolefin,a para-methylstyrene and a para-(halomethylstyrene); and exfoliatedclays that are used as a high impact material. Further, JapaneseUnexamined Application P2000-160024 to Yuichi et al. discloses athermoplastic elastomer composition which can be used as an air barrier,including a blend similar to that disclosed in Li et al.

Elastomeric nanocomposite innerliners and innertubes have also beenformed using a complexing agent and a rubber, where the agent is areactive rubber having positively charged groups and a layered silicateuniformly dispersed therein. See, for example, Kresge et al. U.S. Pat.Nos. 5,665,183 and 5,576,373. This approach uses pre-formed positivelycharged reactive rubber components.

Nanocomposites have also been formed using non-ionic, brominatedcopolymers of isobutylene and para-methylstyrene, and blends of thesecopolymers with other polymers. See, for example, Elspass et al., U.S.Pat. No. 5,807,629, and U.S. Pat. No. 6,034,164.

As described above, these nanocomposites are made by mixing ofelastomers and organoclays either at melt state or in solution; and, dueto the hydrophobic nature of the polymer, the organoclays are typicallymodified to provide better interaction between the clays and thepolymers. The modification process typically involves exchange of Na+cations in the inorganic clay with organic modifiers such as tetra alkylammonium salts. The process is expensive and most modified clays are notexfoliated in polymers or in organic solvent.

SUMMARY OF THE INVENTION

The present invention provides a less costly, more efficient method tomanufacture polymer-clay nanocomposites. The invention also provides apolymer-clay nanocomposite that can include an elastomer; a polymer oroligomer functionalized with a polar group; and a clay. By blending thefunctionalized polymer/oligomer with the elastomer and/or clay, thedispersion of the clay in the elastomer can be enhanced without specificfunctionalization of the elastomer for clay dispersion, and barrierproperties of the resulting blend are similar to blending the clay withpolar functionalized elastomer.

The elastomer can be a halogenated elastomer, such as a halogenatedpolyisobutylene for example, or a halogenated copolymer of isobutyleneand para-methylstyrene as another example. The elastomer can behalogenated with bromine or chlorine. The halogenated elastomer can havefunctional groups, such as halides, ethers, amines, amides, esters,acids, and hydroxyls. In one embodiment, the elastomer is essentiallyfree of polar functionalization, or in another embodiment, thehalogenated elastomer is essentially free of polar functionalizationother than the halogenation. In another embodiment, the elastomer orhalogenated elastomer is less functionalized than the functionalizedpolymer or oligomer.

The elastomer can include a polymer chain E comprising anammonium-functionalized group. The ammonium functionalized group can bedescribed by the following group pendant to the polymer chain E:

wherein R and R¹ are the same or different and are one of a hydrogen, C₁to C₇ alkyls, and primary or secondary alkyl halides; and wherein R², R³and R⁴ are the same or different and are selected from hydrogen, C₁ toC₂₀ alkyls, alkenes or aryls, substituted C₁ to C₂₀ alkyls, alkenes oraryls, C₁ to C₂₀ aliphatic alcohols or ethers, C₁ to C₂₀ carboxylicacids, nitriles, ethoxylated amines, acrylates, esters and ammoniumions.

The polymer or oligomer can be functionalized with between 0.01 and 10weight percent of a polar group in one embodiment; 0.01 weight percentto 10 weight percent of the polymer in one embodiment, and from 0.1weight percent to 8 weight percent in another embodiment, from 0.2 to 7weight percent in yet another embodiment, from 0.2-5.0 weight percent inanother embodiment, from 0.3-3.0 weight percent in another embodiment,and from 0.5 to 2.0 weight percent in another embodiment, wherein adesirable range may be any combination of any upper weight percent limitwith any lower weight percent limit. The polymer or oligomerfunctionalized with a polar group can be a polymer or oligomer of aC₄-C₈ isoolefin. The isoolefin can be isobutylene. The polymer oroligomer can be an interpolymer of a C₄-C₇ isoolefin and analkylstyrene. The polymer or oligomer can be halogenated with bromine orchlorine.

The polar group can be selected from alcohols, ethers, acids,anhydrides, nitriles, amines including ethoxylated amines, acrylates,esters, ammonium ions, and combinations thereof.

The polar group can be derived from an acid anhydride, such as a cyclicanhydride, a symmetric anhydride, a mixed anhydride, or combinationsthereof. The acid anhydride can be a carboxylic anhydride, athioanhydride, a phosphoric anhydride, or mixtures thereof.

In one embodiment, the acid anhydride is a carboxylic acid anhydride. Incertain embodiments, the carboxylic acid anhydride is maleic anhydride,succinic anhydride, or a combination thereof.

In one embodiment, the polar group is derived from an acid. The acid canbe a carboxylic acid, a dicarboxylic acid, a tricarboxylic acid, an oxocarboxylic acid, a peroxy acid, a thiocarboxylic acid, a sulfonic acid,a sulfinic acid, a xanthic acid, sulfenic acid, sulfamic acid, aphosphonic acid, an amic acid, an azinic acid, an azonic acid, ahydroxamic acid, an imidic acid, an imino acid, a nitrosolic acid, anitrolic acid, a hydrazonic acid, or mixtures thereof.

In certain embodiments, the elastomer can have a number averagemolecular weight between 25000 and 500000; between 50000 and 250000 inother embodiments; greater than 50000 in yet other embodiments. Incertain embodiments, the polar polymer or oligomer can have a numberaverage molecular weight between 500 and 100000; less than 25000 inother embodiments; greater than 50000 in other embodiments. In certainembodiments, the elastomer has a number average molecular weight of atleast 100000 and the polar polymer has a molecular weight less than100000; in other embodiments, the elastomer and polar polymer can haveany combination of number average molecular weights, the same ordifferent.

In certain embodiments, the elastomer can be halogenated and the polargroup can be derived from an acid or an acid anhydride. In otherembodiments, the elastomer can be halogenated and partiallyfunctionalized with an amine and the polar group can be derived fromalcohols, ethers, acids, anhydrides, nitriles, acrylates, esters, orcombinations thereof.

In certain embodiments of the nanocomposite, the weight ratio of polarfunctionalized polymer/oligomer to elastomer can be between 0.01:1 and1:1. In other embodiments, the weight ratio of polar functionalizedpolymer/oligomer to elastomer can be between 0.05:1 and 0.5:1; between0.1:1 and 0.25:1; or between any combination of ratios in otherembodiments.

The nanocomposite includes clay, which can be an inorganic clay, anorganoclay, or mixtures thereof. The clay can be a silicate. The claycan be a smectite clay, such as montmorillonite, nontronite, beidellite,bentonite, volkonskoite, laponite, hectorite, saponite, sauconite,magadite, kenyaite, stevensite, vermiculite, halloysite, hydrotalcite,or a combination thereof.

The nanocomposite can include fillers such as calcium carbonate, mica,silica, silicates (for purposes of use as a filler, not clay), talc,titanium dioxide, carbon black, or mixtures thereof. The nanocompositecan incorporate additives including dye, pigment, antioxidant, heat andlight stabilizer, plasticizer, oil, or mixtures thereof. Thenanocomposite can also incorporate curatives including organic peroxide,zinc oxide, zinc stearate, stearic acid, an accelerator, a vulcanizingagent, or mixtures thereof.

The present invention also provides a method to form a nanocompositecomprising combining a halogenated elastomer, a clay, and a polymer oroligomer functionalized with a polar group, each as described above.

The present invention also provides for the improvement of a process tomanufacture a nanocomposite comprising elastomer and a clay, theimprovement comprising introducing a polymer or oligomer functionalizedwith a polar group to the elastomer-clay mixture.

DETAILED DESCRIPTION

This invention describes a process for making polymer/claynanocomposites. The process can produce a nanocomposite of a halogenatedelastomer and a clay, desirably an exfoliated clay, suitable for use asan air barrier. The nanocomposite formed by the process of thisinvention has improved air barrier properties and is suitable for use asan innerliner or innertube.

Definitions

As used herein, the new numbering scheme for the Periodic Table Groupsis used as set forth in CHEMICAL AND ENGINEERING NEWS, 63(5), 27 (1985).

As used herein, “polymer” may be used to refer to homopolymers,copolymers, interpolymers, terpolymers, etc. Likewise, a copolymer mayrefer to a polymer comprising at least two monomers, optionally withother monomers.

As used herein, when a polymer is referred to as comprising a monomer,the monomer is present in the polymer in the polymerized form of themonomer or in the derivative form the monomer. Likewise, when catalystcomponents are described as comprising neutral stable forms of thecomponents, it is well understood by one skilled in the art, that theionic form of the component is the form that reacts with the monomers toproduce polymers.

As used herein, “elastomer” or “elastomeric composition” refers to anypolymer or composition of polymers (such as blends of polymers)consistent with the ASTM D1566 definition. Elastomer includes mixedblends of polymers such as melt mixing and/or reactor blends ofpolymers. The terms may be used interchangeably with the term “rubber.”

As used herein, “phr” is ‘parts per hundred rubber’ and is a measurecommon in the art wherein components of a composition are measuredrelative to a major elastomer component, based upon 100 parts by weightof the elastomer(s) or rubber(s).

As used herein, “isobutylene based elastomer” or “isobutylene basedpolymer” refers to elastomers or polymers comprising at least 70 molepercent repeat units from isobutylene.

As used herein, “isoolefin” refers to any olefin monomer having at leastone carbon having two substitutions on that carbon.

As used herein, “multiolefin” refers to any monomer having two or moredouble bonds, for example, a multiolefin may be any monomer comprisingtwo conjugated double bonds such as a conjugated diene such as isoprene.

As used herein, “nanocomposite” or “nanocomposite composition” refers topolymer systems containing inorganic particles with at least onedimension in the nanometer range within a polymer matrix.

As used herein, “intercalation” refers to the state of a composition inwhich a polymer is present between each layer of a platelet filler. Asis recognized in the industry and by academia, some indicia ofintercalation can be the shifting and/or weakening of detection of X-raylines as compared to that of original platelet fillers, indicating alarger spacing between vermiculite layers than in the original mineral.

As used herein, “exfoliation” refers to the separation of individuallayers of the original inorganic particle, so that polymer can surroundor surrounds each particle. In an embodiment, sufficient polymer ispresent between each platelet such that the platelets are randomlyspaced. For example, some indication of exfoliation or intercalation maybe a plot showing no X-ray lines or larger d-spacing because of therandom spacing or increased separation of layered platelets. However, asrecognized in the industry and by academia, other indicia may be usefulto indicate the results of exfoliation such as permeability testing,electron microscopy, atomic force microscopy, etc.

As used herein, “solvent” refers to any substance capable of dissolvinganother substance. When the term solvent is used it may refer to atleast one solvent or two or more solvents unless specified. In certainembodiments, the solvent is polar; in other embodiments, the solvent isnon-polar.

As used herein, “solution” refers to a uniformly dispersed mixture atthe molecular level or ionic level, of one or more substances (solute)in one or more substances (solvent). For example, solution processrefers to a mixing process that both the elastomer and the modifiedlayered filler remain in the same organic solvent or solvent mixtures.

As used herein, “suspension” refers to a system consisting of a soliddispersed in a solid, liquid, or gas usually in particles of larger thancolloidal size.

As used herein, “emulsion” refers to a system consisting of a liquid orliquid suspension dispersed with or without an emulsifier in animmiscible liquid usually in droplets of larger than colloidal size.

As used herein, “hydrocarbon” refers to molecules or segments ofmolecules containing primarily hydrogen and carbon atoms. In someembodiments, hydrocarbon also includes halogenated versions ofhydrocarbons and versions containing heteroatoms as discussed in moredetail below.

As used herein, “polar group” refers to a group of atoms withasymmetrically arranged polar bonds in which the difference inelectronegativity of bonding atoms, using the Linus Pauling scale ofelectronegativities, is greater than 0.3 and less than 1.7. In contrastto ionic groups in which there is charge separation to facilitate cationexchange with the cations between clay layers, there is generally nocharge separation in polar groups. Polar groups can interact with claysurfaces, but serve as dispersion aids and not generally asintercalates.

Elastomer

The nanocomposite of the present invention includes at least oneelastomer comprising C₄ to C₇ isoolefin derived units. The elastomer canbe halogenated. The isoolefin may be a C₄ to C₇ compound, in oneembodiment selected from isobutylene, isobutene, 2-methyl-1-butene,3-methyl-1-butene, 2-methyl-2-butene, and 4-methyl-1-pentene. Theelastomer may also include other monomer derived units. In oneembodiment, the elastomer includes at least one styrenic monomer, whichmay be any substituted styrene monomer unit, and desirably is selectedfrom styrene, a-methylstyrene or an alkylstyrene (ortho, meta, or para),the alkyl selected from any C₁ to C₅ alkyl or branched chain alkyl. In adesirable embodiment, the styrenic monomer is p-methylstyrene. Inanother embodiment, the elastomer includes at least one multiolefin,which may be a C₄ to C₁₄ diene, conjugated or not, in one embodimentselected from isoprene, butadiene, 2,3-dimethyl-1,3-butadiene, myrcene,6,6-dimethyl-fulvene, hexadiene, cyclopentadiene, methylcyclopentadiene,piperylene and combinations thereof.

In one embodiment, the elastomer includes an isoolefin derived unit, amultiolefin derived unit, and a styrenic derived unit. In anotherembodiment, the elastomer includes an isoolefin derived unit and astyrenic derived unit, and in yet another embodiment the elastomerincludes an isoolefin derived unit and a multiolefin derived unit.

The elastomers in one embodiment of the invention are random elastomericcopolymers of a C₄ to C₇ isoolefin, such as isobutylene and apara-alkylstyrene comonomer, preferably para-methylstyrene containing atleast 80%, more preferably at least 90% by weight of the para-isomer andalso include functionalized interpolymers wherein at least some of thealkyl substituents groups present in the styrene monomer units containbenzylic halogen or some other functional group. In another embodimentof the invention, the interpolymer is a random elastomeric copolymer ofethylene or a C₃ to C₆ α-olefin and a para-alkylstyrene comonomer,preferably para-methylstyrene containing at least 80%, more preferablyat least 90% by weight of the para-isomer and also includefunctionalized interpolymers wherein at least some of the alkylsubstituents groups present in the styrene monomer units containbenzylic halogen or some other functional group. Preferred materials maybe characterized as interpolymers containing the following monomer unitsrandomly spaced along the polymer chain:

wherein R¹⁰ and R¹¹ are independently hydrogen, lower alkyl, preferablyC₁ to C₇ alkyl and primary or secondary alkyl halides and X is afunctional group such as halogen. Preferably R¹⁰ and R¹¹ are hydrogen.Up to 60 mole percent of the para-substituted styrene present in theinterpolymer structure may be the functionalized structure above in oneembodiment, and in another embodiment from 0.1 to 5 mole percent. In yetanother embodiment, the amount of functionalized structure is from 0.4to 1 mole percent.

The functional group X may be halogen or a combination of a halogen andsome other functional group such which may be incorporated bynucleophilic substitution of benzylic halogen with other groups such ascarboxylic acids; carboxy salts; carboxy esters, amides and imides;hydroxy; alkoxide; phenoxide; thiolate; thioether; xanthate; cyanide;nitrile; amino and mixtures thereof. These functionalized isoolefincopolymers, their method of preparation, methods of functionalization,and cure are more particularly disclosed in U.S. Pat. No. 5,162,445, andin particular, the functionalized amines as described below.

Most useful of such functionalized materials are elastomeric randominterpolymers of isobutylene and para-methylstyrene containing from 0.5to 20 mole percent para-methylstyrene, wherein up to 60 mole percent ofthe methyl substituent groups present on the benzyl ring contain abromine or chlorine atom, preferably a bromine atom(para(bromomethylstyrene)), as well as a combination ofpara(bromomethylstyrene) and other functional groups such as ester andether. These halogenated elastomers are commercially available asEXXPRO™ Elastomers (ExxonMobil Chemical Company, Houston Tex.), andabbreviated as “BIMS”.

In a preferred embodiment, the functionality is selected such that itcan react or form polar bonds with functional groups present in thematrix polymer, for example, acid, amino or hydroxyl functional groups,when the polymer components are mixed at high temperatures.

These functionalized interpolymers have a substantially homogeneouscompositional distribution such that at least 95% by weight of thepolymer has a para-alkylstyrene content within 10% of the averagepara-alkylstyrene content of the polymer. Desirable interpolymers arealso characterized by a narrow molecular weight distribution(M_(w)/M_(n)) of less than 5, more preferably less than 2.5, a preferredviscosity average molecular weight in the range of from 200,000 up to2,000,000 and a preferred number average molecular weight in the rangeof from 25,000 to 750,000 as determined by gel permeationchromatography.

The BIMS polymers may be prepared by a slurry polymerization of themonomer mixture using a Lewis acid catalyst, followed by halogenation,preferably bromination, in solution in the presence of halogen and aradical initiator such as heat and/or light and/or a chemical initiatorand, optionally, followed by electrophilic substitution of bromine witha different functional moiety.

Preferred BIMS polymers are brominated polymers that generally containfrom 0.1 to 5 mole percent of bromomethylstyrene groups relative to thetotal amount of monomer derived units in the polymer. In anotherembodiment, the amount of bromomethyl groups is from 0.2 to 3.0 molepercent, and from 0.3 to 2.8 mole percent in yet another embodiment, andfrom 0.4 to 2.5 mole percent in yet another embodiment, and from 0.3 to2.0 in yet another embodiment, wherein a desirable range may be anycombination of any upper limit with any lower limit. Expressed anotherway, preferred copolymers contain from 0.2 to 10 weight percent ofbromine, based on the weight of the polymer, from 0.4 to 6 weightpercent bromine in another embodiment, and from 0.6 to 5.6 weightpercent in another embodiment, are substantially free of ring halogen orhalogen in the polymer backbone chain. In one embodiment of theinvention, the interpolymer is a copolymer of C₄ to C₇ isoolefin derivedunits (or isomonoolefin), para-methylstyrene derived units andpara-(halomethylstyrene) derived units, wherein thepara-(halomethylstyrene) units are present in the interpolymer from 0.4to 3.0 mole percent based on the total number of para-methylstyrene, andwherein the para-methylstyrene derived units are present from 3 weightpercent to 15 weight percent based on the total weight of the polymer inone embodiment, and from 4 weight percent to 10 weight percent inanother embodiment. In another embodiment, the para-(halomethylstyrene)is para-(bromomethylstyrene).

The halogenated elastomer useful in the present invention may alsoinclude a halogenated butyl rubber component. As used herein,“halogenated butyl rubber” refers to both butyl rubber and so-called“star-branched” butyl rubber, described below. In one embodiment of theinvention, the halogenated rubber component is a halogenated copolymerof a C₄ to C₇ isoolefin and a multiolefin. In another embodiment, thehalogenated rubber component is a blend of a polydiene or blockcopolymer, and a copolymer of a C₄ to C₇ isoolefin and a conjugated, ora “star-branched” butyl polymer. The halogenated butyl polymer useful inthe present invention can thus be described as a halogenated elastomercomprising C₄ to C₇ isoolefin derived units, multiolefin derived units,and halogenated multiolefin derived units, and includes both“halogenated butyl rubber” and so called “halogenated star-branched”butyl rubber.

In one embodiment, the halogenated butyl rubber is brominated butylrubber, and in another embodiment is chlorinated butyl rubber. Generalproperties and processing of halogenated butyl rubbers is described inTHE VANDERBILT RUBBER HANDBOOK 105-122 (Robert F. Ohm ed., R.T.Vanderbilt Co., Inc. 1990), and in RUBBER TECHNOLOGY 311-321 (MauriceMorton ed., Chapman & Hall 1995). Butyl rubbers, halogenated butylrubbers, and star-branched butyl rubbers are described by Edward Kresgeand H. C. Wang in 8 KIRK-OTHMER ENCYCLOPEDIA OF CHEMICAL TECHNOLOGY934-955 (John Wiley & Sons, Inc. 4th ed. 1993).

The halogenated rubber component of the present invention includes, butis not limited to, brominated butyl rubber, chlorinated butyl rubber,star-branched polyisobutylene rubber, star-branched brominated butyl(polyisobutylene/isoprene copolymer) rubber;isobutylene-bromomethylstyrene copolymers such asisobutylene/meta-bromomethylstyrene,isobutylene/para-bromomethylstyrene, isobutylene/chloromethylstyrene,halogenated isobutylene cyclopentadiene, andisobutylene/para-chloromethylstyrene, and the like halomethylatedaromatic interpolymers as in U.S. Pat. No. 4,074,035 and U.S. Pat. No.4,395,506; isoprene and halogenated isobutylene copolymers,polychloroprene, and the like, and mixtures of any of the above. Someembodiments of the halogenated rubber component are also described inU.S. Pat. No. 4,703,091 and U.S. Pat. No. 4,632,963.

More particularly, in one embodiment of the brominated rubber componentof the invention, a halogenated butyl rubber is used. The halogenatedbutyl rubber is produced from the halogenation of butyl rubber.Preferably, the olefin polymerization feeds employed in producing thehalogenated butyl rubber of the invention are those olefinic compoundsconventionally used in the preparation of butyl-type rubber polymers.The butyl polymers are prepared by reacting a comonomer mixture, themixture having at least (1) a C₄ to C₇ isoolefin monomer component suchas isobutylene with (2) a multiolefin, or conjugated diene, monomercomponent. The isoolefin is in a range from 70 to 99.5 weight percent byweight of the total comonomer mixture in one embodiment, and 85 to 99.5weight percent in another embodiment. The conjugated diene component inone embodiment is present in the comonomer mixture from 30 to 0.5 weightpercent in one embodiment, and from 15 to 0.5 weight percent in anotherembodiment. In yet another embodiment, from 8 to 0.5 weight percent ofthe comonomer mixture is conjugated diene.

The isoolefin is a C₄ to C₇ compound such as isobutylene, isobutene2-methyl-1-butene, 3-methyl-1-butene, 2-methyl-2-butene, and4-methyl-1-pentene. The multiolefin is a C₄ to C₁₄ conjugated diene suchas isoprene, butadiene, 2,3-dimethyl-1,3-butadiene, myrcene,6,6-dimethyl-fulvene, cyclopentadiene, hexadiene and piperylene. Oneembodiment of the butyl rubber polymer of the invention is obtained byreacting 92 to 99.5 weight percent of isobutylene with 0.5 to 8 weightpercent isoprene, or reacting 95 to 99.5 weight percent isobutylene withfrom 0.5 to 5.0 weight percent isoprene in yet another embodiment.

Halogenated butyl rubber is produced by the halogenation of the butylrubber product described above. Halogenation can be carried out by anymeans, and the invention is not herein limited by the halogenationprocess. Methods of halogenating polymers such as butyl polymers aredisclosed in U.S. Pat. Nos. 2,631,984, 3,099,644, 4,554,326, 4,681,921,4,650,831, 4,384,072, 4,513,116 and 5,681,901. In one embodiment, thehalogen is in the so called II and III structures as discussed in, forexample, RUBBER TECHNOLOGY at 298-299 (1995). In one embodiment, thebutyl rubber is halogenated in hexane diluent at from 40 to 60° C. usingbromine (Br₂) or chlorine (Cl₂) as the halogenation agent. Thehalogenated butyl rubber has a Mooney Viscosity of from 20 to 70 (ML 1+8at 125° C.) in one embodiment, and from 25 to 55 in another embodiment.The halogen content is from 0.1 to 10 weight percent based in on theweight of the halogenated butyl rubber in one embodiment, and from 0.5to 5 weight percent in another embodiment. In yet another embodiment,the halogen weight percent of the halogenated butyl rubber is from 1 to2.2 weight percent.

In another embodiment, the halogenated butyl or star-branched butylrubber may be halogenated such that the halogenation is primarilyallylic in nature. This is typically achieved by such means as freeradical bromination or free radical chlorination, or by such methods assecondary treatment of electrophilically halogenated rubbers, such as byheating the rubber, to form the allylic halogenated butyl andstar-branched butyl rubber. Common methods of forming the allylichalogenated polymer are disclosed by Gardner et al. in U.S. Pat. No.4,632,963; U.S. Pat. No. 4,649,178; U.S. Pat. No. 4,703,091. Thus, inone embodiment of the invention, the halogenated butyl rubber is suchthat the halogenated multiolefin units are primary allylic halogenatedunits, and wherein the primary allylic configuration is present to atleast 20 mole percent (relative to the total amount of halogenatedmultiolefin) in one embodiment, and at least 30 mole percent in anotherembodiment. This arrangement can be described by the structure:

wherein X is a halogen, desirably chlorine or bromine, and q is at least20 mole percent based on the total moles of halogen in one embodiment,and at least 30 mole percent in another embodiment, and from 25 molepercent to 90 mole percent in yet another embodiment.

A commercial embodiment of the halogenated butyl rubber of the presentinvention is Bromobutyl 2222 (ExxonMobil Chemical Company). Its MooneyViscosity is from 27 to 37 (ML 1+8 at 125° C., ASTM 1646, modified), andthe bromine content is from 1.8 to 2.2 weight percent. Anothercommercial embodiment of the halogenated butyl rubber is Bromobutyl 2255(ExxonMobil Chemical Company). Its Mooney Viscosity is from 41 to 51 (ML1+8 at 125° C., ASTM 1646, modified), and the bromine content is from1.8 to 2.2 weight percent. The invention is not limited to thecommercial source of any of the halogenated rubber components.

In another embodiment of the brominated rubber component of theinvention, a branched or “star-branched” halogenated butyl rubber isused. In one embodiment, the star-branched halogenated butyl rubber(“SBHR”) is a composition of a butyl rubber, either halogenated or not,and a polydiene or block copolymer, either halogenated or not. Thehalogenation process is described in detail in U.S. Pat. Nos. 4,074,035,5,071,913, 5,286,804, 5,182,333 and 6,228,978. The invention is notlimited by the method of forming the SBHR. The polydienes/blockcopolymer, or branching agents (hereinafter “polydienes”), are typicallycationically reactive and are present during the polymerization of thebutyl or halogenated butyl rubber, or can be blended with the butyl orhalogenated butyl rubber to form the SBHR. The branching agent orpolydiene can be any suitable branching agent, and the invention is notlimited to the type of polydiene used to make the SBHR.

In one embodiment, the SBHR is typically a composition of the butyl orhalogenated butyl rubber as described above and a copolymer of apolydiene and a partially hydrogenated polydiene selected from the groupincluding styrene, polybutadiene, polyisoprene, polypiperylene, naturalrubber, styrene-butadiene rubber, ethylene-propylene diene rubber,styrene-butadiene-styrene and styrene-isoprene-styrene block copolymers.These polydienes are present, based on the monomer weight percent,greater than 0.3 weight percent in one embodiment, and from 0.3 to 3weight percent in another embodiment, and from 0.4 to 2.7 weight percentin yet another embodiment.

A commercial embodiment of the SBHR of the present invention isBromobutyl 6222 (ExxonMobil Chemical Company), having a Mooney Viscosity(ML 1+8 at 125° C., ASTM 1646, modified) of from 27 to 37, and a brominecontent of from 2.2 to 2.6 weight percent.

The halogenated rubber component is present in the blend of theinvention from 10 to 90 phr in one embodiment, from 20 to 80 phr inanother embodiment, and from 30 to 70 phr in yet another embodiment,wherein a desirable range may be any combination of any upper phr limitwith any lower phr limit.

Functionalized Halogenated Elastomers

The halogen in the above described halogenated polymer can react or formpolar bonds with functional groups present in the matrix polymer, forexample, acid, amino or hydroxyl functional groups, when the componentsare mixed at high temperatures. One embodiment of the present inventionis a nanocomposite comprising a clay and a halogenated elastomercomprising C₄ to C₇ isoolefin derived units; wherein a portion of thehalogen in the elastomer is electrophilically substituted with anamine-functionalized group such that the halogenated elastomer alsocomprises an amine-functionalized monomer unit described by thefollowing group pendant to the elastomer E:

wherein R and R¹ are the same or different and are selected fromhydrogen, C₁ to C₇ alkyls, and primary or secondary alkyl halides; andwherein R², R³ and R⁴ are the same or different and are selected fromhydrogen, C₁ to C₂₀ alkyls, alkenes or aryls, substituted C₁ to C₂₀alkyls, alkenes or aryls, C₁ to C₂₀ aliphatic alcohols or ethers, C₁ toC₂₀ carboxylic acids, nitriles, ethoxylated amines, acrylates, estersand ammonium ions. In a desirable embodiment, at least one of R², R³ andR⁴ are selected from C₁ to C₂₀ alkenes, C₁ to C₂₀ aliphatic alcohols, C₁to C₂₀ aliphatic ethers, C₁ to C₂₀ carboxylic acids, nitriles,ethoxylated amines, acrylates, esters and ammonium ions.

In one embodiment, the halogenated elastomer E comprises C₄ to C₇isoolefin derived units, para-methylstyrene derived units andpara-(halomethylstyrene) derived units.

In another embodiment, the halogenated elastomer E comprises C₄ to C₇isoolefin derived units, multiolefin derived units, and halogenatedmultiolefin derived units.

The functional group pendant to the elastomer E can be further describedas functionalized amine, wherein at least one of R², R³ and R⁴ isselected from C₁ to C₂₀ aliphatic alcohols or ethers, C₁ to C₂₀carboxylic acids, nitriles, esters, ammonium ions, or acrylate groups;wherein the acrylate is described by the following formula:

wherein R⁵, R⁶ and R⁷ are the same or different and are selected fromhydrogen and C₁ to C₇ alkyl or alkenyl.

In another embodiment, the amine-functionalized group is selected fromethoxylated amines having the following structure:

wherein R⁸ is a C₁ to C₂₀ alkyl; and wherein x+y is 2, 5, 10, 15, or 50.

In another embodiment, the amine-functionalized group is selected fromdimethylaminoethylacrylate, dimethylaminomethylacrylate,N-methylamino-bis-2-propanol, N-ethylamino-bis-2-propanol,dimethylaminoethylmethacrylate, diethylaminopropanol,diethylethanolamine, dimethylamino-1-propanol, tripropanolamine,triethanolamine, aminolauric acid, betaine, and combinations thereof.

The amine-functionalized derived unit may be present on the halogenatedelastomer from 0.01 weight percent to 10 weight percent of the elastomerin one embodiment, and from 0.1 weight percent to 8 weight percent inanother embodiment, and from 0.2 to 6 weight percent in yet anotherembodiment, wherein a desirable range may be any combination of anyupper weight percent limit with any lower weight percent limit.

Polar Modified Polymer or Oligomer

A polar oligomer or polymer can be present in compositions and end usearticles of the present invention. The polar polymer can increase theinteraction between the polymer matrix and the clay, facilitatingseparation, dispersion or exfoliation of clay aggregates duringnanocomposite processing, and thus can provide a composite with improvedbarrier properties. The polar component can also minimize clayre-aggregation during compounding when forming end-use products. Incertain embodiments, the polar polymer can have a chemical (chainbackbone) composition similar to the halogenated or functionalizedhalogenated elastomers described above to promote polymer compatibility.The polar group can be selected from alcohols, ethers, acids,anhydrides, nitriles, amines including ethoxylated amines, acrylates,esters, ammonium ions, and combinations thereof.

In one embodiment, the polar polymer can be a reaction product formed byreaction of a polymer with an acid or an acid anhydride. In otherembodiments, the polar polymer can be formed by reaction of a polymerwith an acid anhydride and an initiator. Although acids and acidanhydrides are referred to generally, one skilled in the art recognizesthat incorporation of the acid or acid anhydride into the polymer caninclude derivatives and salts of the acid or acid anhydride.

In one embodiment, the polar polymer can comprise C₄ to C₈ isoolefinderived units. The isoolefin may be a C₄ to C₈ compound, in oneembodiment selected from isobutylene, isobutene, 2-methyl-1-butene,3-methyl-1-butene, 2-methyl-2-butene, and 4-methyl-1-pentene. The polarpolymer may also include other monomer derived units. In one embodiment,the polar polymer includes at least one styrenic monomer, which may beany substituted styrene monomer unit, and desirably is selected fromstyrene, a-methylstyrene or an alkylstyrene (ortho, meta, or para), thealkyl selected from any C₁ to C₅ alkyl or branched chain alkyl. In adesirable embodiment, the styrenic monomer is p-methylstyrene. Inanother embodiment, the polar polymer includes at least one multiolefin,which may be a C₄ to C₁₄ diene, conjugated or not, in one embodimentselected from isoprene, butadiene, 2,3-dimethyl-1,3-butadiene, myrcene,6,6-dimethyl-fulvene, hexadiene, cyclopentadiene, methylcyclopentadiene,piperylene and combinations thereof.

In one embodiment, the polar polymer includes an isoolefin derived unit,a multiolefin derived unit, and a styrenic derived unit. In anotherembodiment, the polar polymer includes an isoolefin derived unit and astyrenic derived unit, and in yet another embodiment the polar polymerincludes an isoolefin derived unit and a multiolefin derived unit. Inother embodiments, the polar polymer can be halogenated orfunctionalized as described above.

In some embodiments, the acid anhydride can be an organic acidanhydride. The acid anhydride can be a carboxylic acid anhydride of oneof the following general formulae:

where R¹ and R² can be the same or different and are selected from C₁ toC₂₀ alkyls, alkenes or aryls, substituted C₁ to C₂₀ alkyls, alkenes oraryls, C₁ to C₂₀ aliphatic alcohols or ethers, nitriles, ethoxylatedamines, acrylates, esters and ammonium ions. In some embodiments theacid anhydride can be maleic anhydride. In other embodiments the acidanhydride can be succinic anhydride.

In other embodiments, the acid anhydride can be a phosphoric acidanhydride or a thioanhydride. In yet other embodiments, the polar groupcan be a carboxamide.

In some embodiments, the acid can be an organic acid. The acid can be acarboxylic acid, a dicarboxylic acid, a tricarboxylic acid, an oxocarboxylic acid, a peroxy acid, and the like. In other embodiments, theacid can be a thiocarboxylic acid, a sulfonic acid, a sulfinic acid, axanthic acid, sulfenic acid, sulfamic acid, a phosphonic acid, an amicacid, an azinic acid, an azonic acid, a hydroxamic acid, an imidic acid,an imino acid, a nitrosolic acid, a nitrolic acid, a hydrazonic acid, ormixtures thereof.

In other embodiments, the polar oligomer or polymer can be formed byreaction of a polymer with an acid anhydride and an initiator. In aparticular embodiment, an initiator may be a member of the peroxidefamily. Particularly useful peroxides include peresters, perketals, andperoxycarbonates. In some embodiments, the peroxide can be aperoxybenzoate. Commercial quantities of these compounds can be obtainedfrom Akzo Nobel, Arkema, Aztec, and others. As is well known to oneskilled in the art, such peroxides are selected on the basis of theirdecomposition rates at different temperatures. Such half-lifeinformation is available from the suppliers. The concentration ofinitiator used to react the polymer and the acid or acid anhydride canrange from about 0 ppm to about 600 ppm or more. In still otherembodiments of the present invention the initiator may include acombination of initiators. One skilled in the art will realize thatthese concentrations are not limiting and any concentrations yielding apolymer product with the desirable properties may be employed.

For example, in some embodiments, the polar polymer can be apolyisobutylene succinic anhydride, a reaction product ofpolyisobutylene and succinic anhydride. In other embodiments, the polaroligomer or polymer can be a reaction product of the halogenatedelastomer described above and maleic anhydride. In other embodiments,the halogenated elastomer and maleic anhydride are reacted in thepresence of an initiator such as tert-butyl peroxybenzoate for example.

The acid or acid anhydride derived unit may be present on the polymerfrom 0.01 weight percent to 10 weight percent of the polymer in oneembodiment, and from 0.1 weight percent to 8 weight percent in anotherembodiment, from 0.2 to 7 weight percent in yet another embodiment, from0.2-5.0 weight percent in another embodiment, and from 0.3-3.0 weightpercent in another embodiment, wherein a desirable range may be anycombination of any upper weight percent limit with any lower weightpercent limit. Where the elastomer may contain functional groups, thepolar polymer can contain a higher content of functional groups and/or adifferent functional group or groups, e.g. a type of functional groupthat is more polar than the functional groups of the elastomer, so as toimprove exfoliation, intercalation, gas barrier properties, and polymerblend compatibility.

In certain embodiments, the nanocomposite of the present invention caninclude a halogenated elastomer and a polar polymer, where the polarpolymer can enhance exfoliation, blend compatibility, and gas barrierproperties without the need for additional functionalization of thehalogenated elastomer, as described above. In addition to eliminatingprocess steps, minimizing or avoiding functionalization of thehalogenated elastomer can enhance the curability of the composite as thearomatic halomethyl groups provide a wide choice of crosslinkingreactions that can be used.

The interactions between the polar polymers and between the polarpolymers and other components of the nanocomposite of the presentinvention can enhance air barrier properties. Polar or other ionicinteractions between the composite molecules can limit the area throughwhich oxygen or other gases can permeate, thus improving the barrierproperties of the composite.

In some embodiments, suitable polar polymers derived from anisomonoolefin and an acid or acid anhydride include polymers having anumber average molecular weight (Mn) of at least about 1,000, preferablyat least about 10,000, more preferably at least about 30,000. Thecopolymers also, preferably, have a ratio of weight average molecularweight (Mw) to number average molecular weight (Mn), i.e., Mw/Mn of lessthan about 6, preferably less than about 4, more preferably less thanabout 2.5.

In other embodiments, suitable polar oligomers or low polymers have anumber average molecular weight (Mn) of at least about 500, preferablyat least about 1,000, more preferably at least about 2000. The oligomersalso, preferably, have a ratio of weight average molecular weight (Mw)to number average molecular weight (Mn), i.e., Mw/Mn of less than about6, preferably less than about 4, more preferably less than about 2.5.

The combined polymer component of the nanocomposites of the presentinvention may comprise at least one polymer or elastomer as described inany of the above polymer or elastomers or may comprise any combinationof at least two or more of the polymers and elastomers described above.In an embodiment, the elastomer or polymer comprises at least oneisobutylene-based polymer. In another embodiment, the elastomer orpolymer comprises at least one isobutylene-based polymer and at leastone other rubber. In yet another embodiment, the elastomer or polymercomprises at least two or more isobutylene-based polymers.

Secondary Rubber Component

A secondary rubber or “general purpose rubber” component may be presentin compositions and end use articles of the present invention. Theserubbers include, but are not limited to, natural rubbers, polyisoprenerubber, poly(styrene-co-butadiene) rubber (SBR), polybutadiene rubber(BR), poly(isoprene-co-butadiene) rubber (IBR),styrene-isoprene-butadiene rubber (SIBR), ethylene-propylene rubber(EPM), ethylene-propylene-diene rubber (EPDM), polysulfide, nitrilerubber, propylene oxide polymers, star-branched butyl rubber andhalogenated star-branched butyl rubber, brominated butyl rubber,chlorinated butyl rubber, star-branched polyisobutylene rubber,star-branched brominated butyl (polyisobutylene/isoprene copolymer)rubber; poly(isobutylene-co-p-methylstyrene) and halogenatedpoly(isobutylene-co-p-methylstyrene), such as, for example, terpolymersof isobutylene derived units, p-methylstyrene derived units, andp-bromomethylstyrene derived units, and mixtures thereof.

A desirable embodiment of the secondary rubber component present isnatural rubber. Natural rubbers are described in detail by Subramaniamin RUBBER TECHNOLOGY 179-208 (Maurice Morton, Chapman & Hall 1995).Desirable embodiments of the natural rubbers of the present inventionare selected from Malaysian rubber such as SMR CV, SMR 5, SMR 10, SMR20, and SMR 50 and mixtures thereof, wherein the natural rubbers have aMooney viscosity at 100° C. (ML 1+4) of from 30 to 120, more preferablyfrom 40 to 65. The Mooney viscosity test referred to herein is inaccordance with ASTM D-1646.

Polybutadiene (BR) rubber is another desirable secondary rubber usefulin the composition of the invention. The Mooney viscosity of thepolybutadiene rubber as measured at 100° C. (ML 1+4) may range from 35to 70, from 40 to about 65 in another embodiment, and from 45 to 60 inyet another embodiment. Some commercial examples of these syntheticrubbers useful in the present invention are NATSYNTM (Goodyear ChemicalCompany), and BUDENE™ 1207 or BR 1207 (Goodyear Chemical Company). Adesirable rubber is high cis-polybutadiene (cis-BR). By“cis-polybutadiene” or “high cis-polybutadiene”, it is meant that1,4-cis polybutadiene is used, wherein the amount of cis component is atleast 95%. An example of a high cis-polybutadiene commercial productused in the composition is BUDENE™ 1207.

Rubbers of ethylene and propylene derived units such as EPM and EPDM arealso suitable as secondary rubbers. Examples of suitable comonomers inmaking EPDM are ethylidene norbornene, 1,4-hexadiene, dicyclopentadiene,as well as others. These rubbers are described in RUBBER TECHNOLOGY260-283 (1995). A suitable ethylene-propylene rubber is commerciallyavailable as VISTALON™ (ExxonMobil Chemical Company, Houston Tex.).

In another embodiment, the secondary rubber is a halogenated rubber aspart of the terpolymer composition. The halogenated butyl rubber isbrominated butyl rubber, and in another embodiment is chlorinated butylrubber. General properties and processing of halogenated butyl rubbersis described in THE VANDERBILT RUBBER HANDBOOK 105-122 (Robert F. Ohmed., R.T. Vanderbilt Co., Inc. 1990), and in RUBBER TECHNOLOGY 311-321(1995). Butyl rubbers, halogenated butyl rubbers, and star-branchedbutyl rubbers are described by Edward Kresge and H. C. Wang in 8KIRK-OTHMER ENCYCLOPEDIA OF CHEMICAL TECHNOLOGY 934-955 (John Wiley &Sons, Inc. 4th ed. 1993).

The secondary rubber component of the present invention includes, but isnot limited to at least one or more of brominated butyl rubber,chlorinated butyl rubber, star-branched polyisobutylene rubber,star-branched brominated butyl (polyisobutylene/isoprene copolymer)rubber; halogenated poly(isobutylene-co-p-methylstyrene), such as, forexample, terpolymers of isobutylene derived units, p-methylstyrenederived units, and p-bromomethylstyrene derived units (BrIBMS), and thelike halomethylated aromatic interpolymers as in U.S. Pat. No.5,162,445; U.S. Pat. No. 4,074,035; and U.S. Pat. No. 4,395,506;halogenated isoprene and halogenated isobutylene copolymers,polychloroprene, and the like, and mixtures of any of the above. Someembodiments of the halogenated rubber component are also described inU.S. Pat. No. 4,703,091 and U.S. Pat. No. 4,632,963.

In one embodiment of the invention, a so called semi-crystallinecopolymer (“SCC”) is present as the secondary “rubber” component.Semi-crystalline copolymers are described in WO 00/69966. Generally, theSCC is a copolymer of ethylene or propylene derived units and a-olefinderived units, the α-olefin having from 4 to 16 carbon atoms in oneembodiment, and in another embodiment the SCC is a copolymer of ethylenederived units and α-olefin derived units, the α-olefin having from 4 to10 carbon atoms, wherein the SCC has some degree of crystallinity. In afurther embodiment, the SCC is a copolymer of 1-butene derived units andanother α-olefin derived unit, the other α-olefin having from 5 to 16carbon atoms, wherein the SCC also has some degree of crystallinity. TheSCC can also be a copolymer of ethylene and styrene.

The secondary rubber component of the elastomer composition may bepresent in a range from up to 90 phr in one embodiment, from up to 50phr in another embodiment, from up to 40 phr in another embodiment, andfrom up to 30 phr in yet another embodiment. In yet another embodiment,the secondary rubber is present from at least 2 phr, and from at least 5phr in another embodiment, and from at least 5 phr in yet anotherembodiment, and from at least 10 phr in yet another embodiment. Adesirable embodiment may include any combination of any upper phr limitand any lower phr limit. For example, the secondary rubber, eitherindividually or as a blend of rubbers such as, for example NR and BR,may be present from 5 phr to 90 phr in one embodiment, and from 10 to 80phr in another embodiment, and from 30 to 70 phr in yet anotherembodiment, and from 40 to 60 phr in yet another embodiment, and from 5to 50 phr in yet another embodiment, and from 5 to 40 phr in yet anotherembodiment, and from 20 to 60 phr in yet another embodiment, and from 20to 50 phr in yet another embodiment, the chosen embodiment dependingupon the desired end use application of the composition.

Fillers, Curatives and Other Additives

The composition of the invention may also include one or more fillercomponents such as calcium carbonate, clay, mica, silica and silicates,talc, titanium dioxide, and carbon black. As used herein, fillers do notinclude inorganic clay and/or organoclay particles forming part of thenanocomposite matrix, e.g. clay particles having a dimension in thenanometer range, but larger clay particles can be used as a filler inthe nanocomposites, if desired. In one embodiment, the filler is carbonblack or modified carbon black. The preferred filler is semi-reinforcinggrade carbon black present at a level of from 10 to 150 phr of theblend, more preferably from 30 to 120 phr. Useful grades of carbon blackas described in RUBBER TECHNOLOGY 59-85 (1995) range from N 110 to N990.More desirably, embodiments of the carbon black useful in, for example,tire treads are N229, N351, N339, N220, N234 and N110 provided in ASTM(D3037, D1510, and D3765). Embodiments of the carbon black useful in,for example, sidewalls in tires are N330, N351, N550, N650, N660, andN762. Embodiments of the carbon black useful in, for example,innerliners for tires are N550, N650, N660, N762, and N990.

The composition of this invention may optionally include curativesystems which are capable of curing the functionalized elastomericcopolymer component of the blend to provide vulcanizable compositions.Suitable curative systems for the elastomeric copolymer component of thepresent invention include organic peroxides, zinc oxide in combinationwith zinc stearate or stearic acid and, optionally, one or more of thefollowing accelerators or vulcanizing agents: Permalux(di-ortho-tolylguanidine salt of dicatechol borate), HVA-2 (m-phenylenebis maleimide), Zisnet (2, 4, 6- trimercapto-5 triazine), ZDEDC (zincdiethyl dithiocarbamate) and other dithiocarbamates, Tetrone A(dipenta-methylene thiuram hexasulfide), Vultac-5 (alkylated phenoldisulfide), SP1045 (phenol formaldehyde resin), SP1056 (brominated alkylphenol formaldehyde resin), DPPD. (diphenyl phenylene diamine),salicyclic acid (o-hydroxy benzoic acid), wood rosin (abietic acid), andTMTDS (tetramethyl thiuram disulfide) in combination with sulfur. Thecomposition may also be cured using ultraviolet light or electronirradiation.

The compositions of the invention may also contain other conventionaladditives such as dyes, pigments, antioxidants, heat and lightstabilizers, plasticizers, oils and other ingredients as known in theart.

Blending of the fillers, additives, and/or curative components may becarried out by combining the desired components and the nanocomposite ofthe present invention in any suitable mixing device such as a Banbury™mixer, Brabender™ mixer or preferably a mixer/extruder and mixing attemperatures in the range of 120° C. up to 300° C. under conditions ofshear sufficient to allow the components to become uniformly dispersedwithin the polymer to form the nanocomposite.

The composition of this invention may be extruded, compression molded,blow molded or injection molded into various shaped articles includingfibers, films, industrial parts such as automotive parts, appliancehousings, consumer products, packaging and the like. The resultingarticles exhibit both high impact strength and low vapor permeability.In particular, the composition described herein is useful for airbarriers such as bladders, and automotive (including truck, commercialand/or passenger) or aircraft innerliners and innertubes.

Clays

The nanocomposites of the present invention can include swellableinorganic clay. Swellable layered inorganic clay materials suitable forthe purposes of this invention include natural or syntheticphyllosilicates, particularly smectic clays such as montmorillonite,nontronite, beidellite, volkonskoite, laponite, hectorite, saponite,sauconite, magadite, kenyaite, stevensite and the like, as well asvermiculite, halloysite, aluminate oxides, hydrotalcite and the like.These layered clays generally comprise particles containing a pluralityof silicate platelets having a thickness of 8-12 Å tightly boundtogether at interlayer spacings of 4 Å or less, and contain exchangeablecations such as Na⁺, Ca⁺², K⁺ or Mg⁺² present at the interlayersurfaces.

The layered clay can be exfoliated by suspending the clay in a watersolution. Preferably, the concentration of clay in water is sufficientlylow to minimize the interaction between clay particles and to fullyexfoliate the clay. In one embodiment, the aqueous slurry of clay canhave a clay concentration of between 0.1 and 5.0 weight percent; between0.1 and 3.0 weight percent in other embodiments.

In certain embodiments, an aqueous slurry of clay can be prepared bystirring clay and water at room temperature for a time sufficient toexfoliate the clay. In one embodiment, the clay and water can be stirredfor between 0.25 and 24 hours. The clay and water can be stirred forbetween 4 and 16 hours, or between 10 and 14 hours, in otherembodiments.

In other embodiments, the clay can be mixed with an organic liquid toform a clay dispersion. The clay can be an inorganic clay or anorganically modified clay; the organic liquid can be miscible orimmiscible in water. In certain embodiments, the dispersion can have aclay concentration of between 0.1 and 5.0 weight percent; between 0.1and 3.0 weight percent in other embodiments.

The layered clay can also be intercalated and exfoliated by treatmentwith organic molecules (swelling or exfoliating “agents” or “additives”)capable of undergoing ion exchange reactions with the cations present atthe interlayer surfaces of the layered silicate. Suitable exfoliatingadditives include cationic surfactants such as ammonium ion, alkylaminesor alkylammonium ion (primary, secondary, tertiary and quaternary),phosphonium or sulfonium derivatives of aliphatic, aromatic orarylaliphatic amines, phosphines and sulfides. Desirable amine compounds(or the corresponding ammonium ion) are those with the structureR¹²R¹³R¹⁴N, wherein R¹², R¹³, and R¹⁴ are C₁ to C₃₀ alkyls or alkenes inone embodiment, C₁ to C₂₀ alkyls or alkenes in another embodiment, whichmay be the same or different. In one embodiment, the exfoliating agentis a so called long chain tertiary amine, wherein at least R¹² is a C₁₄to C₂₀ alkyl or alkene.

The exfoliating agent can also be a diamine compound (or thecorresponding ammonium or diammonium ion), such as diaminoalkane,N-alkyl-diaminoalkane, N,N-dialkyl-diaminoalkyl,N,N,N′-trialkyl-diaminoalkane, N,N,N′,N′-tetraalkyl-diaminoalkane, orthe like. Desirable diamines can have the structure R¹⁸R¹⁹N-R²⁰-NR²¹R²²,wherein R¹⁸, R¹⁹, R²⁰, R²¹, and R²² are the same or different C₁ to C₃₀alkyls or alkenes, or C₁ to C₂₀ alkyls or alkenes. When a long chaindiamine is desired, at least one of the N-alkyl or N-alkene groups hasfrom 8 to 30 carbon atoms, preferably from 14 to 20 carbon atoms.Specific non-limiting, illustrative examples includeN-coco-1,3-diaminopropane, N-oleyl-1,3-diaminopropane,N-tallow-1,3-diaminopropane,N,N,N′-trimethyl-N′-tallow-1,3-diaminopropane, and so on.

Another class of exfoliating additives include those which can becovalently bonded to the interlayer surfaces. These include polysilanesof the structure —Si(R¹⁵)₂R¹⁶ where R¹⁵ is the same or different at eachoccurrence and is selected from alkyl, alkoxy or oxysilane and R¹⁶ is anorganic radical compatible with the matrix polymer of the composite.

Other suitable exfoliating additives include protonated amino acids andsalts thereof containing 2-30 carbon atoms such as 12-aminododecanoicacid, epsilon-caprolactam and like materials. Suitable swelling agentsand processes for intercalating layered silicates are disclosed in U.S.Pat. Nos. 4,472,538, 4,810,734, 4,889,885 as well as WO92/02582.

In a preferred embodiment of the invention, the exfoliating additive oradditives are capable of reaction with the halogen sites on theinterpolymer to form complexes which help exfoliate the clay. In oneembodiment, the additive includes all primary, secondary and tertiaryamines and phosphines; alkyl and aryl sulfides and thiols; and theirpolyfunctional versions. Desirable additives include: long-chaintertiary amines such as N,N-dimethyl-octadecylamine,N,N-dioctadecyl-methylamine, so called dihydrogenatedtallowalkyl-methylamine and the like, and amine-terminatedpolytetrahydrofuran; long-chain thiol and thiosulfate compounds likehexamethylene sodium thiosulfate.

The exfoliating additive such as described herein is present in thecomposition in an amount to achieve optimal air retention as measured bythe permeability testing described herein. For example, the additive maybe present from 0.1 to 20 phr in one embodiment, and from 0.2 to 15 phrin yet another embodiment, and from 0.3 to 10 phr in yet anotherembodiment. The exfoliating additive may be added to the composition atany stage; for example, the additive may be added to the interpolymer,followed by addition of the clay, or may be added to the interpolymerand clay mixture; or the additive may be first blended with the clay,followed by blending with the interpolymer in yet another embodiment.

In another embodiment of the invention, improved interpolymerimpermeability is achieved by the presence of at least onepolyfunctional curative. An embodiment of such polyfunctional curativescan be described by the formula Z-R¹⁷-Z′, wherein R¹⁷ is one of a C₁ toC₁₅ alkyl, C₂ to C₁₅ alkenyl, and C₆ to C₁₂ cyclic aromatic moiety,substituted or unsubstituted; and Z and Z′ are the same or different andare one of a thiosulfate group, mercapto group, aldehyde group,carboxylic acid group, peroxide group, alkenyl group, or other similargroup that is capable of crosslinking, either intermolecularly orintramolecularly, one or more strands of a polymer having reactivegroups such as unsaturation. So-called bis-thiosulfate compounds are anexample of a desirable class of polyfunctional compounds included in theabove formula. Non-limiting examples of such polyfunctional curativesare as hexamethylene bis(sodium thiosulfate) and hexamethylenebis(cinnamaldehyde), and others are well known in the rubber compoundingarts. These and other suitable agents are disclosed in, for example, theBLUE BOOK, MATERIALS, COMPOUNDING INGREDIENTS, MACHINERY AND SERVICESFOR RUBBER (Don. R. Smith, ed., Lippincott & Petto Inc. 2001). Thepolyfunctional curative, if present, may be present in the compositionfrom 0.1 to 8 phr in one embodiment, and from 0.2 to 5 phr in yetanother embodiment.

Treatment with the swelling agents described above results inintercalation or “exfoliation” of the layered platelets as a consequenceof a reduction of the ionic forces holding the layers together andintroduction of molecules between layers which serve to space the layersat distances of greater than 4 Å, preferably greater than 9 Å. Thisseparation allows the layered silicate to more readily sorbpolymerizable monomer material and polymeric material between the layersand facilitates further delamination of the layers when the intercalateis shear mixed with matrix polymer material to provide a uniformdispersion of the exfoliated layers within the polymer matrix.

The amount of clay or exfoliated clay incorporated in the nanocompositesin accordance with this invention is sufficient to develop animprovement in the mechanical properties or barrier properties of thenanocomposite, for example, tensile strength or oxygen permeability.Amounts of clay in the nanocomposite generally will range from 0.5 to 10weight percent in one embodiment, and from 1 to 5 weight percent inanother embodiment, based on the polymer content of the nanocomposite.Expressed in parts per hundred rubber, the clay or exfoliated clay maybe present from 1 to 30 phr in one embodiment, and from 5 to 20 phr inanother embodiment.

Nanocomposite Processing

Nanocomposites can be formed using a variety of processes. For example,in commonly assigned U.S. application Ser. No. 11/183,361 by Gong etal., filed Jul. 18, 2005, (2005B093) there is disclosed a method forpreparing clay-butyl rubber nanocomposites from an emulsion of rubbersolution and aqueous clay dispersion in which the clay can be aninorganic clay. As another example of nanocomposite processing, incommonly assigned U.S. application Ser. No. 11/184,000 by Weng et al.,also filed Jul. 18, 2005, (2005B092) there is disclosed a method forpreparing clay-butyl rubber nanocomposites by preparing a concentratednanocomposite from a slipstream of the rubber and blending theconcentrate with a main rubber stream.

Melt Blending:

The nanocomposite of the present invention can be formed by a polymermelt blending process. Blending of the components can be carried out bycombining the polymer components and the clay in the form of anintercalate in any suitable mixing device such as a Banbury™ mixer,Brabender™ mixer or preferably a mixer/extruder and mixing attemperatures in the range of 120° C. up to 300° C. under conditions ofshear sufficient to allow the clay intercalate to exfoliate and becomeuniformly dispersed within the polymer to form the nanocomposite.

Emulsion Processes:

The nanocomposite of the present invention can also be formed by anemulsion processes. In one embodiment, the emulsion process can comprisemixing an aqueous slurry of inorganic clay with a polymer solution(cement). The mixing should be sufficiently vigorous to form emulsionsor micro-emulsions. In some embodiments, the emulsions can be formed asan aqueous solution or suspension in an organic solution. Standardmethods and equipment for both lab and large-scale production, includingbatch and continuous processes may be used to produce the polymericnanocomposites of the invention.

In certain embodiments, a nanocomposite is produced by a processcomprising contacting Solution A comprising water and at least onelayered clay with Solution B comprising a solvent and at least oneelastomer; and removing the solvent and water from the contact productof Solution A and Solution B to recover a nanocomposite. In certainembodiments, the emulsion is formed by subjecting the mixture toagitation using a high-shear mixer.

In some embodiments, a nanocomposite is produced by a process comprisingcontacting Solution A comprising water and at least one layered claywith Solution B comprising a solvent and at least one elastomer, whereinthe contacting is performed in the presence of an emulsifier orsurfactant.

The emulsions of the present invention are formed by conventionalemulsion technology, that is, subjecting a mixture of the hydrocarbon,water and surfactant, when used, to sufficient shearing, as in acommercial blender or its equivalent for a period of time sufficient forforming the emulsion, e.g., generally at least a few seconds. Forgeneral emulsion information, see generally, “Colloidal Systems andInterfaces”, S. Ross and I. D. Morrison, J. W. Wiley, NY, 1988. Theemulsion can be allowed to remain in emulsion form, with or withoutcontinuous or intermittent mixing or agitation, with or without heatingor other temperature control, for a period sufficient to enhanceexfoliation of the clay, from 0.1 to 100 hours or more in oneembodiment, from 1 to 50 hours in another embodiment, and from 2 to 20hours in another embodiment.

When used, the surfactant concentration is sufficient to allow theformation of a relatively stable emulsion. Preferably, the amount ofsurfactant employed is at least 0.001 weight percent of the totalemulsion, more preferably about 0.001 to about 3 weight percent, andmost preferably 0.01 to less than 2 weight percent.

Cationic surfactants useful in preparing the emulsions of this inventioninclude tertiary amines, diamines, polyamines, amine salts, as well asquaternary ammonium compounds. Non-ionic surfactants useful in preparingthe emulsions of this invention include alkyl ethoxylates, linearalcohol ethoxylates, alkyl glucosides, amide ethoxylates, amineethoxylates (coco-, tallow-, and oleyl-amine ethoxylates for example),phenol ethoxylates, and nonyl phenol ethoxylates.

Solution Blending:

The nanocomposite of the present invention can also be formed bysolution blending, such as described in commonly assigned U.S.application Ser. No. 60/585,629 by Weng et al., filed Jul. 6, 2004,(2004B085) for example. In certain embodiments, a nanocomposite isproduced by a process comprising contacting Solution A comprising asolvent comprising a hydrocarbon and at least one layered filler or claywith Solution B comprising a solvent and at least one elastomer, andremoving the solvents from the contact product of Solution A andSolution B to form a nanocomposite.

In the previous embodiments, the layered filler may be a layered claytreated with organic molecules as described above. In yet anotherembodiment, a nanocomposite is produced by a process comprisingcontacting at least one elastomer and at least one layered filler in asolvent; and removing the solvent from the contact product to form ananocomposite.

In another embodiment, a nanocomposite is produced by a processcomprising contacting at least one elastomer and at least one layeredfiller in a solvent mixture comprising two solvents; and removing thesolvent mixture from the contact product to form a nanocomposite.

In still another embodiment, a nanocomposite is produced by a processcomprising contacting at least one elastomer and at least one layeredfiller in a solvent mixture comprising at least two or more solvents;and removing the solvent mixture from the contact product to form ananocomposite.

In another embodiment, a nanocomposite is produced by a process to forma contact product comprising dissolving at least one elastomer and thendispersing at least one layered filler in a solvent or solvent mixturecomprising at least two solvents; and removing the solvent mixture fromthe contact product to form a nanocomposite.

In yet another embodiment, a nanocomposite is produced by a process toform a contact product comprising dispersing at least one layered fillerand then dissolving at least one elastomer in a solvent or solventmixture comprising at least two solvents; and removing the solventmixture from the contact product to form a nanocomposite.

In the embodiments described above, solvents may be present in theproduction of the nanocomposite composition from 30 to 99 wt %,alternatively from 40 to 99 wt %, alternatively from 50 to 99 wt %,alternatively from 60 to 99 wt %, alternatively from 70 to 99 wt %,alternatively from 80 to 99 wt %, alternatively from 90 to 99 wt %,alternatively from 95 to 99 wt %, based upon the total wt of thecomposition.

Additionally, in certain embodiments, when two or more solvents areprepared in the production of the nanocomposite composition, eachsolvent may comprise from 0.1 to 99.9 vol %, alternatively from 1 to 99vol %, alternatively from 5 to 95 vol %, and alternatively from 10 to 90vol %, with the total volume of all solvents present at 100 vol %.

In still other embodiments, a nanocomposite formed from an abovedescribed process to improve the air impermeability of an elastomer hasan oxygen transmission rate of 150 mm.cc/[m².day] at 40° C. or lower asmeasured on cured nanocomposite compositions or articles as describedherein.

Alternatively, the oxygen transmission rate is 150 mm.cc/[m².day] at 40°C. or lower as measured on cured nanocomposite compounds as describedherein; the oxygen transmission rate is 140 mm.cc/[m².day] at 40° C. orlower as measured on cured nanocomposite compounds as described herein;the oxygen transmission rate is 130 mm.cc/[m².day] at 40° C. or lower asmeasured on cured nanocomposite compounds as described herein; theoxygen transmission rate is 120 mm.cc/[m2.day] at 40° C. or lower asmeasured on cured nanocomposite compounds as described herein; theoxygen transmission rate is 110 mm.cc/[m².day] at 40° C. or lower asmeasured on cured nanocomposite compounds as described herein; theoxygen transmission rate is 100 mm.cc/[m².day] at 40° C. or lower asmeasured on cured nanocomposite compounds as described herein; theoxygen transmission rate is 90 mm.cc/[m².day] at 40° C. or lower asmeasured on cured nanocomposite compounds as described herein; or, theoxygen transmission rate is 80 mm.cc/[m².day] at 40° C. or lower asmeasured on cured nanocomposite compounds as described herein.

The composition of this invention may be extruded, compression molded,blow molded or injection molded into various shaped articles includingfibers, films, industrial parts such as automotive parts, appliancehousings, consumer products, packaging and the like. The resultingarticles exhibit both high impact strength and low vapor permeability.In particular, the composition described herein is useful for airbarriers such as bladders, and automotive (including truck, commercialand/or passenger) or aircraft innerliners and innertubes.

Permeability Testing

For each of the following examples, the nanocomposites formed wereanalyzed for permeability properties using the following method. Incertain embodiments, 36 grams of the clay-rubber mixture was loaded intoa Brabender® mixer at a temperature of 130-145° C. and mixed with 20grams of carbon black (N660) for 7 minutes. The mixture was furthermixed with a curatives package of 0.33 g stearic acid, 0.33 g Kadox®911, and 0.33 g MBTS at 40° C. and 40 rpm for 3 minutes. The resultingrubber compounds were milled, compression molded and cured at 170° C.All specimens were compression molded with slow cooling to providedefect free pads. A compression and curing press was used for rubbersamples. Typical thickness of a compression molded pad is around 15 mil.using an Arbor press, 2″ diameter disks were then punched out frommolded pads for permeability testing. These disks were conditioned in avacuum oven at 60° C. overnight prior to the measurement. The oxygenpermeation measurements were done using a Mocon™ OX-TRAN 2/61permeability tester at 40° C. under the principle of R. A. Pasternak et.al. in 8 JOURNAL OF POLYMER SCIENCE: PART A-2 467 (1970). Disks thusprepared were mounted on a template and sealed with a vacuum grease. 10psi nitrogen was kept on one side of the disk, whereas the other side is10 psi oxygen. Using the oxygen sensor on the nitrogen side, increase inoxygen concentration on the nitrogen side with time could be monitored.The time required for oxygen to permeate through the disk, or for oxygenconcentration on the nitrogen side to reach a constant value, isrecorded and used to determine the oxygen permeability. Permeability wasmeasured as oxygen transmission rate on a Mocon™ WX-TRAN 2/61 at 40° C.Where multiple samples were prepared using the same procedure,permeation rates are given for each sample.

In certain embodiments, a useful formulation for property evaluationwould be as follows: Material I.D. Parts Elastomer/Clay 100 + x parts ofclay Carbon black N660 60.0  Stearic Acid 1.0 ZnO Kadox ™ 911 1.0 MBTS1.0

Carbon black N660 can be obtained from, e.g., Cabot Corp. (Billerica,Mass.). Stearic acid, a cure agent, can be obtained from, e.g., C. K.Witco Corp. (Taft, La.), Kadox® 911, an activator, can be obtained fromC. P. Hall (Chicago, Ill.). MBTS, 2-mercaptobenzothiazole disulfide, canbe obtained from R. T. Vanderbilt (Norwalk, Conn.) or Elastochem(Chardon, Ohio).

In certain examples below, polyisobutylene succinic anhydride (PIBSA) isused, and can be obtained from INFENIUM, USA (Linden, N.J.). The PIBSAgrades available from INFENIUM can have a number average molecularweight ranging from 600 to about 2200. As used in the examples, PIBSA 48has a number average molecular weight of about 2200.

For certain jurisdictions, the invention also provides for:

-   1. A nanocomposite comprising:    -   an elastomer;    -   a polymer or oligomer functionalized with a polar group; and a        clay.-   2. The nanocomposite of claim 1 wherein the elastomer comprises a    halogenated isobutylene elastomer.-   3. The elastomer of claim 1 or 2 wherein the elastomer comprises an    interpolymer of a C₄ to C₇ isoolefin and an alkylstyrene.-   4. The nanocomposite of any one of claims 1-3 wherein the elastomer    comprises functional groups selected from the group consisting of    halides, ethers, amines, amides, esters, acids, and hydroxyls.-   5. The nanocomposite of any one of claims 1-4 wherein the elastomer    is halogenated with bromine or chlorine.-   6. The nanocomposite of any one of claims 1-5 wherein the polar    group comprises from 0.1 to 10 weight percent of the polymer or    oligomer, and a weight ratio of the functionalized polymer or    oligomer to the elastomer is between 0.01:1 and 1:1.-   7. The nanocomposite of any one of claims 1-5 wherein the polar    group comprises from 0.5 to 7.0 weight percent of the polymer or    oligomer, and a weight ratio of the functionalized polymer or    oligomer to the elastomer is between 0.05:1 and 0.5:1.-   8. The nanocomposite of any one of claims 1-7 wherein the polymer or    oligomer comprises a polymer or oligomer of a C₄-C₈ isoolefin.-   9. The nanocomposite of claim 10 wherein the isoolefin comprises    isobutylene.-   10. The nanocomposite of any one of claims 1-9 wherein the polymer    or oligomer comprises an interpolymer of a C₄-C₇ isoolefin and an    alkylstyrene.-   11. The nanocomposite of any one of claims 1-10 wherein the polar    group is selected from the group consisting of alcohols, ethers,    acids, anhydrides, nitriles, amines, acrylates, esters, ammonium    ions, and combinations thereof.-   12. The nanocomposite of any one of claims 1-11 wherein the polar    group is derived from an acid anhydride.-   13. The nanocomposite of claim 12 wherein the anhydride comprises a    cyclic anhydride, a symmetric anhydride, a mixed anhydride, or    combinations thereof.-   14. The nanocomposite of claim 12 wherein the acid anhydride is a    carboxylic anhydride, a thioanhydride, a phosphoric anhydride, or    mixtures thereof.-   15. The nanocomposite of claim 12 wherein the acid anhydride is a    carboxylic acid anhydride.-   16. The nanocomposite of claim 12 wherein the acid anhydride is    maleic anhydride.-   17. The nanocomposite of claim 9 wherein the polar group is derived    from maleic anhydride.-   18. The nanocomposite of claim 12 wherein the acid anhydride is    succinic anhydride.-   19. The nanocomposite of claim 8 wherein the polar group is derived    from succinic anhydride.-   20. The nanocomposite of any one of claims 1-9 wherein the polar    group is derived from an acid.-   21. The nanocomposite of claim 20 wherein the acid comprises a    carboxylic acid, a dicarboxylic acid, a tricarboxylic acid, an oxo    carboxylic acid, a peroxy acid, a thiocarboxylic acid, a sulfonic    acid, a sulfinic acid, a xanthic acid, sulfenic acid, sulfamic acid,    a phosphonic acid, an amic acid, an azinic acid, an azonic acid, a    hydroxamic acid, an imidic acid, an imino acid, a nitrosolic acid, a    nitrolic acid, a hydrazonic acid, or mixtures thereof.-   22. The nanocomposite of any one of claims 1-21 wherein the    elastomer has a number average molecular weight between 25000 and    500000 and the polar polymer has a number average molecular between    500 and 100000.-   23. The nanocomposite of claim 22 wherein the elastomer has a number    average molecular weight of at lest 100000.-   24. The nanocomposite of claim 22 wherein the polar polymer or    oligomer has a number average molecular weight less than 100000.-   25. The nanocomposite of claim 22 wherein the polar polymer or    oligomer has a number average molecular weight of at least 500.-   26. The nanocomposite of any one of claims 1-25 wherein the clay    comprises an inorganic clay.-   27. The nanocomposite of any one of claims 1-25 wherein the clay    comprises an organoclay.-   28. The nanocomposite of any one of claims 1-25 wherein the clay    comprises a silicate.-   29. The nanocomposite of any one of claims 1-25 wherein the clay    comprises smectite clay.-   30. The nanocomposite of claim 29 wherein the smectite clay    comprises montmorillonite, nontronite, beidellite, bentonite,    volkonskoite, laponite, hectorite, saponite, sauconite, magadite,    kenyaite, stevensite, vermiculite, halloysite, hydrotalcite, or a    combination thereof.-   31. The nanocomposite of claim 29 wherein the smectite clay    comprises montmorillonite, bentonite, vermiculite, or a combination    thereof.-   32. The nanocomposite of any one of claims 1-31 comprising calcium    carbonate, mica, silica, silicates, talc, titanium dioxide, carbon    black, or mixtures thereof.-   33. The nanocomposite of any one of claims 1-32 comprising dye,    pigment, antioxidant, heat and light stabilizer, plasticizer, oil,    or mixtures thereof.-   34. The nanocomposite of any one of claims 1-33 comprising organic    peroxide, zinc oxide, zinc stearate, stearic acid, an accelerator, a    vulcanizing agent, or mixtures thereof.-   35. The nanocomposite of claim 1 wherein the elastomer is    halogenated and the polar group is derived from an acid or an acid    anhydride.-   36. The nanocomposite of claim 1 wherein the elastomer is    halogenated and functionalized with an amine and the polar group is    derived from the group consisting of alcohols, ethers, acids,    anhydrides, nitriles, acrylates, esters, and combinations thereof.-   37. A method to form a nanocomposite comprising contacting a    halogenated elastomer, a clay, and a polymer or oligomer    functionalized with a polar group.-   38. The method of claim 37 wherein the polar group is derived from    an acid anhydride.-   39. The method of claim 37 wherein the polar group is derived from    an acid.-   40. The method of any one of claims 37-39 comprising incorporating a    curative into the nanocomposite.-   41. The method of claim 40 comprising curing the nanocomposite.-   42. In a process to manufacture a nanocomposite comprising an    elastomer and a clay, the improvement comprising introducing a    polymer or oligomer functionalized with a polar group to the    elastomer-clay mixture.-   43. The improvement of claim 42 wherein the polar group is derived    from an acid.-   44. The improvement of claim 42 wherein the polar group is derived    from an acid anhydride.

EXAMPLES Examples 1-8

Cyclohexane (1.7 L) was added to a jacketed glass reactor and heated to60° C. EXXPRO™ elastomer (MDX 03-1: 10 wt % of PMS, 0.85 mol % Br) wasthen added to the heated reactor. After all of the polymer wascompletely dissolved, 16 grams of clay and a polyisobutylene succinicanhydride (PIBS 48, available from INFINIUM, USA) solution in 50 mL ofcyclohexane were added to the reactor and stirred for 40 minutes. Thecement was then poured out and the solvent was evaporated. Theprecipitate was dried under vacuum at 100° C. overnight. ComparativeExamples 1-4 were made in a similar fashion, excluding addition ofPIBSA.

Forty (40) grams of the dried clay-rubber mixture was loaded into aBrabender™. After adding carbon black N660 (22.2 grams), the mixture wasmixed for 6 minutes at 140° C. and 60 rpm, and discharged from themixer. The discharged mixture is reloaded into the Brabender™ and mixedat 50° C. and 40 rpm for 30 seconds. Curatives (Stearic Acid, 0.37grams; Kadox® 911, 0.37 grams; MBTS, 0.37 grams) were then added to theBrabender™ and the components mixed for 4 minutes. The material was thencollected for permeation measurement as described above; permeationresults are detailed in Table 1 below. TABLE 1 Permeation results forExamples 1-8 and Comparative Examples 1-4. PIBSA Exxpro ™ Clay 48Permeation Rate Example # (grams) Type (grams) (cc * mm/m² * day) Comp.Ex. 1 200 Cloisite ® 6A 0 103.6; 103.44 1 196 Cloisite ® 6A 4 93.7; 87.82 192 Cloisite ® 6A 8 98.6; 96.0 Comp. Ex. 2 200 Cloisite ® 20A 0 93.6;91.0 3 196 Cloisite ® 20A 4 91.1; 91.4 4 192 Cloisite ® 20A 8 84.4; 82.7Comp. Ex. 3 200 Cloisite ® 25A 0 86.6; 81.0 5 196 Cloisite ® 25A 4 75.2;74.4 6 192 Cloisite ® 25A 8 85.9; 85.7 Comp. Ex. 4 200 Cloisite ® 30B 092.7; 91.4 7 196 Cloisite ® 30B 4 86.0; 89.3 8 192 Cloisite ® 30B 889.9; 92.3

Examples 9-14

The Brabender™ was heated to 150° C. and set for 60 rpm. Exxpro™ (MDX03-1: 10 wt % of PMS, 0.85 mol % Br) and PIBSA (properties are as givenabove) were loaded into the Brabender™ and mixed for one minute. Clay,as necessary, was added to the mixture and mixed for 8 minutes. Theresulting mixture was then recovered from the mixer. 36 grams of therecovered mixture was loaded into the Brabender™ and mixed with carbonblack (N660, 20 grams) for 8 minutes at 150° C. and 60 rpm. Curativeswere then added to the mixture (stearic acid, Kadox® 911, and MBTS, 0.33grams each) and stirred at 40° C. and 40 rpm for 3 minutes. The materialwas then collected for permeation measurement as described above;permeation results are detailed in Table 2 below. TABLE 2 Conditions andresults for Experiments 9-14. Exxpro ™ Clay PIBSA 48 Permeation RateExample # (grams) Type (grams) (cc * mm/m² * day) 9 45.08 Cloisite ® 25A0.92 93.4; 91.8 10 44.16 Cloisite ® 25A 1.84 86.7; 82.4 11 45.08Cloisite ® 6A 0.92 108.7; 104.8 12 44.16 Cloisite ® 6A 1.84 102.2; 98.013 45.08 None 0.92 104.6; 109.8 14 44.16 None 1.84 107.3; 110.8

Examples 15-16

Fifty-five grams of XP50 rubber (an isobutylene+para-methylstyrenecopolymer having a number average molecular weight of approximately60000, and a molecular weight distribution of approximately 2.05) and 3grams maleic anhydride were loaded into a Brabender™ at 180° C. and 60rpm and mixed for 1 minute. In a separate beaker, Luperox® P (tert butylperoxybenzoate 1.4 mL) was dissolved in acetone (3 mL) and the solutionwas slowly added to the Brabender™. After all Luperox® solution wasadded, the mixture was mixed for an additional 8 minutes. The Brabender™was then heated to 210° C. and the mixture was mixed for 2 minutes,causing the Luperox® to initiate a reaction; the maleic anhydride,peroxybenzoate, and polymer react to form a maleic anydydride modifiedXP50 (MAXP50). This procedure was repeated to generate sufficientMAXP50, with the resulting product combined and dried vacuum at 100° C.for 10 hours. The reaction resulted in an MAXP50 having approximately0.5 weight percent anhydride functionality (analyses indicated between0.2 and 3.0 weight percent incorporation of the anhydride onto thepolymer).

In a 2-liter jacketed reactor, MAXP50 (9.6 grams) and Exxpro™ (MDX 03-1:10 wt % of PMS, 0.85 mol % Br) (50.4 grams) were dissolved incyclohexane (700 mL). Water was added to the mixture, if necessary, andthe solution was stirred for 5 minutes. Cloisite® 25A, 4.8 grams, wasthen added, and the mixture stirred for an additional 20 minutes. Theresulting solution was collected in a container and the solvent wasevaporated. The product was dried under vacuum at 100° C. overnight.

Forty (40) grams of the dried clay-rubber mixture was loaded into aBrabender™ and mixed with carbon black (N660, 22.2 grams) and mixed form8 minutes at 140° C. and 60 rpm. Curatives were then added to themixture (stearic acid, Kadox® 911, and MBTS, 0.33 grams each) andstirred at 40° C. and 40 rpm for 3 minutes. The material was thencollected for permeation measurement as described above; permeationresults are detailed in Table 3 below. TABLE 3 Mixture and PermeationResults for Examples 15 and 16. Modified Permeation Example Exxpro ™Clay XP50 Water Rate (cc * # (grams) Type (grams) (mL) mm/m² * day) 1550.4 Cloisite ® 9.6 0 88.0; 92.4 25A 16 50.4 Cloisite ® 9.6 175 84.8;80.7 25A

Examples 17-24

Fifty-five grams of XP50 rubber and maleic anhydride as indicated inTable 4 (3 or 4.5 g) were loaded into a Brabender™ at 180° C. and 60 rpmand mixed for 1 minute. In a separate beaker, Luperox® P (tert butylperoxybenzoate; 1.4 or 2.1 mL) was dissolved in acetone (3 or 4.5 mL),and the solution was slowly added to the Brabender™. After all Luperox®solution was added, the mixture was mixed for an additional 8 minutes.The Brabender™ was then heated to 210° C. and the mixture was mixed for2 minutes, causing the Luperox® to initiate a reaction; the maleicanhydride, peroxybenzoate, and polymer react to form a maleic anhydridemodified XP50 (MAXP50). This procedure was repeated to generatesufficient MAXP50 at each anhydride level, with the resulting productcombined and dried under vacuum at 100° C. for 10 hours.

In a 2-liter jacketed reactor, MAXP50 (9.6 grams) and Exxpro™ (MDX 03-1:10 wt % of PMS, 0.85 mol % Br) (50.4 grams) were dissolved incyclohexane (700 mL). Water was added to the mixture, if necessary, andthe solution was stirred for 5 minutes. Cloisite® 25A, 4.8 grams, wasthen added, and the mixture stirred for an additional 20 minutes. Theresulting solution was collected in a container and the solvent wasevaporated. The product was dried under vacuum at 100° C. overnight.

Forty (40) grams of the dried clay-rubber mixture were loaded into aBrabender™ and mixed with carbon black (N660, 20.0 grams) for 8 minutesat 140° C. and 60 rpm. Curatives were then added to the mixture (stearicacid, Kadox® 911, and MBTS, 0.33 grams each) with stirring at 50° C. and40 rpm for 3 minutes. The material was then collected for permeationmeasurement as described above; permeation results are detailed in Table4 below. TABLE 4 Mixture and Permeation Results for Examples 17-24.Maleic Luperox ® P Anhydride (for MAXP (for MAXP Water Water PermeationRate 50) 50) (for clay-rubber pH (for clay- (of cured material) Example# (mL) (grams) prep.) (mL) rubber prep.) (cc * mm/m² * day) 17 1.4 3.0 0N/A 92.2; 99.0 18 1.4 3.0 175 5 96.5; 95.2 19 1.4 3.0 175 7 93.8; 93.3;88.6; 89.9 20 1.4 3.0 175 9 83.3; 87.3; 88.9; 89.6 21 2.1 4.5 0 N/A90.6; 91.4; 96.2; 97.3 22 2.1 4.5 175 5 77.4; 79.7; 77.6; 85.3 23 2.14.5 175 7 77.3; 85.4; 85.9; 81.6 24 2.1 4.5 175 9 78.5; 79.2; 79.2; 80.1

Examples 25-30

Fifty-five grams of XP50 rubber and the amount of maleic anhydrideindicated in Table 5 were loaded into a Brabender™ at 180° C and 60 rpmand mixed for 1 minute. In a separate beaker, Luperox® P (tert butylperoxybenzoate; 1.4 mL) was dissolved in acetone (5 mL), and thesolution was slowly added to the Brabender™. After all Luperox® solutionwas added, the mixture was mixed for an additional 8 minutes. TheBrabender™ was then heated to 210° C. and the mixture was mixed for 2minutes, causing the Luperox® to initiate a reaction; the maleicanhydride, peroxybenzoate, and polymer react to form a maleic anhydridemodified XP50 (MAXP50). This procedure was repeated to generatesufficient MAXP50 at each anhydride level, with the resulting productcombined and dried under vacuum at 100° C. for 10 hours.

A glass bottle was filled with cyclohexane (750 mL). MAXP50 and clay(6.4 g each) were added to the cyclohexane and mixed on a shaker for 6hours. Exxpro™ (MDX 03-1: 10 wt % of PMS, 0.85 mol % Br) (73.6 g) wasthen added and the solution mixed on a shaker for 3 hours to dissolvethe polymer. The resulting solution was collected and the solvent wasevaporated. The product was dried under vacuum at 70° C. for 10 hoursand further dried on a mill for 10 to 15 minutes at 130° C.

Thirty-six (36) grams of the dried clay-rubber mixture were then loadedinto a Brabender™ and mixed with carbon black (N660, 20.0 grams) for 8minutes at 140° C. and 60 rpm. Curatives were then added to the mixture(stearic acid, Kadox® 911, and MBTS, 0.33 grams each) and stirred at 50°C. and 40 rpm for 3 minutes. The material was then collected forpermeation measurement as described above; permeation results aredetailed in Table 5 below. TABLE 5 Mixture and Permeation Results forExamples 25-30. Permeation Maleic Rate Anhydride (of cured Luperox ® P(for MAXP material) (for MAXP 50) 50) (cc * mm/ Example # (mL) (grams)Clay Type m² * day) 25 1.99 3.0 Cloisite ® 25A 77.7; 76.1 26 1.99 3.0Cloisite ® 6A 97.5; 92.7 27 3.98 6.0 Cloisite ® 25A 89.3; 89.2 28 3.986.0 Cloisite ® 6A 92.9; 88.0 29 5.96 9.0 Cloisite ® 25A 81.2; 77.7 305.96 9.0 Cloisite ® 6A 91.8; 86.1

Examples 31-35

EXXPRO™ (MDX 03-1, 80 g) and PIBSA (polyisobutylene succinic anhydride)were dissolved in 700 mL cyclohexane in a glass container. The solutionwas transferred into a mantled reactor. The container was washed with100 mL of cyclohexane and the washing solution was also added to thereactor. Then, 200 mL water was added with proper pH values (for pH=5,HCl solution was used; for pH=9, NaOH solution was used). After stirringthe mixture at 70° C., 3.4 g of CLOISITE® Na+ was added, and the mixturewas stirred for 30 minutes. The mixture was poured out and the solventwas evaporated. The sample was dried under vacuum for 24 hours at 100°C. The permeability of the resulting nanocomposite was tested asdescribed above and the results are presented in Table 6. TABLE 6Nanocomposites formed with PIBSA. Clay Type: CLOISITE ® Na+ PIBSA (MW =950) Water Water Permeation Rate Example (g) (mg) (mL) pH (mm · cc/m2 ·day @ 40° C.) 31 3.4 1.0 200 Neutral 99.5; 101.0 32 3.4 1.5 200 Neutral99.5; 107.64 33 3.4 2.2 200 Neutral 103.01; 103.2 34 3.4 1.5 200 5104.76; 100.6 35 3.4 1.5 200 9 100.78; 96.94

Examples 36-40

EXXPRO™ (MDX 03-1 80 g) and PIBSA 48 (INFENIUM, USA) were dissolved in700 mL cyclohexane in a glass container. The solution was transferredinto a glass reactor at 50° C. The container was washed with 100 mLcyclohexane and the washing solution was added to the reactor. Then 200mL water were added with proper pH values (for pH=5, HCl solution wasused; for pH=9, NaOH solution was used). After the solution was mixedwith clay for 30 minutes, the solution was precipitated withisopropanol. The product was dried under vacuum for 24 hours at 100° C.The permeability of the resulting nanocomposite was tested as describedabove and the results are presented in Table 7. TABLE 7 Nanocompositesformed with Amine PIBSA 48. Clay Type: Amine CLOISITE ® Na+ PIBSA 48Water Water Permeation Rate Example (g) (g) (mL) pH (mm · cc/m2 · day @40° C.) 36 3.4 2 200 Neutral 98.67; 97.41 37 3.4 4 200 Neutral 100.0;102.02 38 3.4 6 200 Neutral 96.25; 95.69 39 3.4 4 200 5 100.31; 101.1340 3.4 4 200 9 102.15; 103.5

Embodiments of the final nanocomposite of the present invention areuseful as air barriers, such as used in producing innerliners for motorvehicles. In particular, the nanocomposites are useful in innerlinersand innertubes for articles such as truck tires, bus tires, passengerautomobile, motorcycle tires, and the like.

While the present invention has been described and illustrated byreference to particular embodiments, those of ordinary skill in the artwill appreciate that the invention lends itself to many differentvariations not illustrated herein. For these reasons, then, referenceshould be made solely to the appended claims for purposes of determiningthe true scope of the present invention.

All priority documents are herein fully incorporated by reference forall jurisdictions in which such incorporation is permitted. Further, alldocuments cited herein, including testing procedures, are herein fullyincorporated by reference for all jurisdictions in which suchincorporation is permitted.

1. A nanocomposite comprising: an elastomer; a polymer or oligomerfunctionalized with a polar group; and a clay.
 2. The nanocomposite ofclaim 1 wherein the elastomer comprises a halogenated isobutyleneelastomer.
 3. The elastomer of claim 1 wherein the elastomer comprisesan interpolymer of a C₄ to C₇ isoolefin and an alkylstyrene.
 4. Thenanocomposite of claim 1 wherein the elastomer comprises functionalgroups selected from the group consisting of halides, ethers, amines,amides, esters, acids, and hydroxyls.
 5. The nanocomposite of claim 1wherein the elastomer is halogenated with bromine or chlorine.
 6. Thenanocomposite of claim 1 wherein the polar group comprises from 0.1 to10 weight percent of the polymer or oligomer, and a weight ratio of thefunctionalized polymer or oligomer to the elastomer is between 0.01:1and 1:1.
 7. The nanocomposite of claim 1 wherein the polar groupcomprises from 0.5 to 7.0 weight percent of the polymer or oligomer, anda weight ratio of the functionalized polymer or oligomer to theelastomer is between 0.05:1 and 0.5:1.
 8. The nanocomposite of claim 1wherein the polymer or oligomer comprises a polymer or oligomer of aC₄-C₈ isoolefin.
 9. The nanocomposite of claim 10 wherein the isoolefincomprises isobutylene.
 10. The nanocomposite of claim 1 wherein thepolymer or oligomer comprises an interpolymer of a C₄-C₇ isoolefin andan alkylstyrene.
 11. The nanocomposite of claim 1 wherein the polargroup is selected from the group consisting of alcohols, ethers, acids,anhydrides, nitriles, amines, acrylates, esters, ammonium ions, andcombinations thereof.
 12. The nanocomposite of claim 1 wherein the polargroup is derived from an acid anhydride.
 13. The nanocomposite of claim12 wherein the anhydride comprises a cyclic anhydride, a symmetricanhydride, a mixed anhydride, or combinations thereof.
 14. Thenanocomposite of claim 12 wherein the acid anhydride is a carboxylicanhydride, a thioanhydride, a phosphoric anhydride, or mixtures thereof.15. The nanocomposite of claim 12 wherein the acid anhydride is acarboxylic acid anhydride.
 16. The nanocomposite of claim 12 wherein theacid anhydride is maleic anhydride.
 17. The nanocomposite of claim 11wherein the polar group is derived from maleic anhydride.
 18. Thenanocomposite of claim 12 wherein the acid anhydride is succinicanhydride.
 19. The nanocomposite of claim 10 wherein the polar group isderived from succinic anhydride.
 20. The nanocomposite of claim 1wherein the polar group is derived from an acid.
 21. The nanocompositeof claim 20 wherein the acid comprises a carboxylic acid, a dicarboxylicacid, a tricarboxylic acid, an oxo carboxylic acid, a peroxy acid, athiocarboxylic acid, a sulfonic acid, a sulfinic acid, a xanthic acid,sulfenic acid, sulfamic acid, a phosphonic acid, an amic acid, an azinicacid, an azonic acid, a hydroxamic acid, an imidic acid, an imino acid,a nitrosolic acid, a nitrolic acid, a hydrazonic acid, or mixturesthereof.
 22. The nanocomposite of claim 1 wherein the elastomer has anumber average molecular weight between 25000 and 500000 and the polarpolymer has a number average molecular between 500 and
 100000. 23. Thenanocomposite of claim 22 wherein the elastomer has a number averagemolecular weight of at lest
 100000. 24. The nanocomposite of claim 22wherein the polar polymer or oligomer has a number average molecularweight less than
 25000. 25. The nanocomposite of claim 22 wherein thepolar polymer or oligomer has a number average molecular weight of atleast
 500. 26. The nanocomposite of claim 1 wherein the clay comprisesan inorganic clay.
 27. The nanocomposite of claim 1 wherein the claycomprises an organoclay.
 28. The nanocomposite of claim 1 wherein theclay comprises a silicate.
 29. The nanocomposite of claim 1 wherein theclay comprises smectite clay.
 30. The nanocomposite of claim 29 whereinthe smectite clay comprises montmorillonite, nontronite, beidellite,bentonite, volkonskoite, laponite, hectorite, saponite, sauconite,magadite, kenyaite, stevensite, vermiculite, halloysite, hydrotalcite,or a combination thereof.
 31. The nanocomposite of claim 29 wherein thesmectite clay comprises montmorillonite, bentonite, vermiculite, or acombination thereof.
 32. The nanocomposite of claim 1 further comprisingcalcium carbonate, mica, silica, silicates, talc, titanium dioxide,carbon black, or mixtures thereof.
 33. The nanocomposite of claim 1further comprising dye, pigment, antioxidant, heat and light stabilizer,plasticizer, oil, or mixtures thereof.
 34. The nanocomposite of claim 1further comprising organic peroxide, zinc oxide, zinc stearate, stearicacid, an accelerator, a vulcanizing agent, or mixtures thereof.
 35. Thenanocomposite of claim 1 wherein the elastomer is halogenated and thepolar group is derived from an acid or an acid anhydride.
 36. Thenanocomposite of claim 1 wherein the elastomer is halogenated andfunctionalized with an amine and the polar group is derived from thegroup consisting of alcohols, ethers, acids, anhydrides, nitriles,acrylates, esters, and combinations thereof.
 37. The nanocomposite ofclaim 1 wherein a weight ratio of polymer to elastomer is between 0.01:1and 1.0:1.0.
 38. A method to form a nanocomposite comprising contactinga halogenated elastomer, a clay, and a polymer or oligomerfunctionalized with a polar group.
 39. The method of claim 38 whereinthe polar group is derived from an acid anhydride.
 40. The method ofclaim 38 wherein the polar group is derived from an acid.
 41. The methodof claim 38 further comprising incorporating a curative into thenanocomposite.
 42. The method of claim 41 further comprising curing thenanocomposite.
 43. In a process to manufacture a nanocompositecomprising elastomer and a clay, the improvement comprising introducinga polymer or oligomer functionalized with a polar group to theelastomer-clay mixture.
 44. The improvement of claim 43 wherein thepolar group is derived from an acid.
 45. The improvement of claim 43wherein the polar group is derived from an acid anhydride.